Separation method

ABSTRACT

The invention provides a method for the separation of solids from a semi-solid viscous mass, the method comprising treating a solids-containing semi-solid viscous mass in an apparatus comprising a separating member incorporating a substantially flat solid surface and a supporting member, wherein the separating member is adapted to selectively impart directional momentum to the solids, thereby facilitating separation of the solids from the semi-solid viscous mass. Preferably the separating member comprises a substantially flat solid surface adapted for vibrational motion, the vibrational motion causing the solids material to be displaced from the remainder of the semi-solid viscous mass.

FIELD OF THE INVENTION

The present invention relates to a method for the separation of wastematerials. More specifically, it provides a rapid and convenient methodfor the separation of solid debris from wet sludges.

BACKGROUND TO THE INVENTION

In many industries, there is frequently a requirement for the separationof solid materials and objects from liquids, and many techniques arewell known for achieving such separations. Depending upon the nature ofthe solids and liquids which require separation, and the quantitiesinvolved, methods such as sedimentation, centrifugation and, mostcommonly, filtration are generally appropriate to such situations andprovide an efficient means of separating solid and liquid components.

On occasions, however, such methods may prove to be inappropriate to thetask at hand, and alternative means of separation have to be found.Thus, for example, centrifugation may not always be applicable to largescale separations, whilst filtration is often problematical whenhandling particularly viscous liquids, since rates of filtration can beexcruciatingly slow, making processes uneconomic; indeed, in extremecircumstances, the method may prove to be impossible to perform, sincefilter media become clogged and liquids are unable to pass through.Indeed, when mixtures of very high viscosity are involved, it is oftenimpossible to achieve any sort of separation by means of filtrationtechniques, since it becomes impossible to find filter media ofappropriate gauge to allow a liquid component to pass whilst retainingsolid materials in the filter, so either the filtrate comprises allcomponents, nothing is retained in the filter, and no separation isachieved, or the filter media becomes immediately blocked, with the sameend result. Even the filtration technique often known as screening,which relies on filtration of a medium through coarse screens, can beprone to such difficulties. It is these problems with viscous media thatthe present invention seeks to address, by providing a method ofseparation which allows for the separation of solid components from suchmedia.

A typical prior art method for dealing with such difficulties has beenbased on the reduction of the viscosity of these highly viscous mediaprior to attempting separation, and the simplest means to achieve suchan objective is by dilution of the media. Most conveniently, of course,dilution is achieved by the addition of water, which is a simple andrelatively cheap procedure. However, whilst such a course of action isoften successful in facilitation separation of components, since theless viscous medium obtained is generally more readily subjected toprocesses such as filtration, the associated consequences are highlyundesirable, since copious quantities of effluent—usually aqueouseffluent—have to be dealt with following the separation process. Hence,a further consideration of the present inventors is the minimisation ofeffluent problems by the avoidance of dilution techniques in the methodof the invention.

Thus, the present invention seeks to provide a method by which solidobjects and components may, rapidly and efficiently, be separated andremoved from viscous media, including highly viscous, non-filterablesludges. The invention also seeks to provide a method which provides areliable and repeatable means of effecting the separation of suchmaterials, and which is not prone to the failures commonly associatedwith the methods of the prior art in such circumstances.

The present inventors have investigated the use of mechanical forceswhich selectively impart momentum to the components of said media forthe purpose of achieving the required separation and, somewhatsurprisingly, have found that it is possible to achieve such separationby the application of vibrational technology, since it has been foundthat, in certain vibrational modes, a suitably disposed surface showsthe degree of selectivity in imparting momentum which is required toachieve the separation of solid objects and components from viscousmedia.

STATEMENTS OF INVENTION

Thus, according to the present invention, there is provided a method forthe separation of solids from a semi-solid viscous mass, said methodcomprising treating a solids-containing semi-solid viscous mass in anapparatus comprising a separating member incorporating a substantiallyflat solid surface and a supporting member, wherein said separatingmember is adapted to selectively impart directional momentum to saidsolids, thereby facilitating separation of said solids from saidsemi-solid viscous mass.

Said separating member is preferably attached to and supported by asupporting member such that said separating member is disposed at anangle close to, but slightly displaced from, the horizontal. Preferably,said separating member is disposed at an angle of between 1° and 10°from the horizontal, more preferably between 2° and 5°, most preferablyaround 3° from the horizontal.

Said separating member comprises a substantially flat solid surface,preferably comprising a tray or plate, the surface of which preferablydemonstrates a different degree of adhesiveness to the solids than tothe remainder of the semi-solid mass, thereby further facilitating theseparation of the materials. Preferably, therefore, the material formingthe surface of the separating member may be chosen to provide aseparating member which allows for an additional degree of separation ofthe materials in question on the basis of the different adhesiveness ofthe solids and the remainder of the semi-solid mass. Said substantiallyflat solid surface does not comprise a screen or other porous surface,since the method of the present invention does not rely on filtration toachieve separation of the components of said solids-containingsemi-solid viscous mass.

Said separating member is adapted to selectively impart directionalmomentum to the solids in the semi-solid viscous mass, and comprises asubstantially flat solid surface adapted for vibrational motion. Thus,it is found that by applying a force to said separating member, so as toimpart vibrational motion to said member, separation of solids from theremainder of the semi-solid mass is achieved rapidly and efficiently.Preferably, said vibrational motion is imparted to said member so as toimpart directional momentum to said solid particulate material, andthereby cause its displacement in a substantially horizontal directionalong said separating member and also in an upward direction away fromthe horizontal. In a particularly preferred embodiment said vibrationalmotion comprises a combination of vibrational motion in the plane of theseparating member and in a direction perpendicular to the plane of theseparating member; thus, the imparted vibrational motion comprises acombination of horizontal vibrational motion and vertical vibrationalmotion.

Said vibrational motion may be imparted by any convenient means,typically by the application of mechanical and/or electromagnetic forcesusing, for example, an out of balance motor drive or an electromagnet.Preferably, electromagnets are used for imparting vibrational motion,especially for smaller system, as they offer a better degree of control.

Typically, the frequency of the applied vibrational motion is in theregion of from 5-50 Hz, preferably from 10-30 Hz, most preferably from15-20 Hz, with amplitude in the plane of the separating member being inthe region of from 2-30 mm, preferably 5-20 mm, most preferably 10-15mm.

Preferably said separating member comprises a substantially flat solidsurface comprising a tray or plate which additionally comprisesperimeter members attached to the edges of said separating member anddisposed substantially perpendicularly to said substantially flat solidsurface, with the proviso that one edge of said separating member doesnot comprise a perimeter member. In this way, the separated solids areable to be removed from the separating member during operation, whilstthe remainder of the semi-solid viscous mass is retained on saidseparating member. Preferably, in operation, the separating member isdisposed with the edge that does not comprise a perimeter member abovethe horizontal.

In the most preferred embodiment, said separating member comprises atray or plate which is rectangular in shape, and three of the four sidescomprise a perimeter member, whilst the fourth side does not include aperimeter member. In operation, the separating member is disposed withsaid fourth side above the horizontal, such that the surface of theseparating member slopes down from said fourth side to the parallelopposite side of the member, which is disposed below the horizontal.Preferably, said separating member is attached to the supporting memberby means of the remaining two sides of the rectangular member,perpendicular to and adjacent said fourth side.

Said supporting member may be any member suitable to support saidseparating member such that said separating member is disposed at anangle close to, but slightly displaced from, the horizontal. Thus, anyconvenient form of support may be employed which provides theappropriate degree of strength and elevation above ground level.

Preferably, said separating member is movably attached to saidsupporting member. Most preferably, said separating member is rotatablyattached to said supporting member, allowing for said separating memberto be conveniently disposed at an angle slightly displaced from thehorizontal. In the said embodiment, it is convenient, following removalof the solids, to reverse the angle of displacement of the separatingmember from the horizontal, such that the side which does not include aperimeter member is then disposed below the horizontal, thus allowingthe remainder of the semi-solid viscous mass to be conveniently removedfrom said separating member.

In the context of the present invention, said solids-containingsemi-solid viscous mass comprises a semi-solid mass of high viscosity,typically a sludge, and said solids may incorporate solid objects orsubstances, or solid particulate material. Thus, for example, the methodof the invention is particularly suited to the removal of solid objects,such as machinery parts, from industrial sludges, small boulders fromclay-like soils, discrete pieces of slate from slate sludges, anddiscrete solid objects from waste sludges. Specific applications of thistype of separation are found in the nuclear industry, wherein theremoval of solid debris from sticky sludges is a common requirement as,for example, in the treatment of corroded cladding from Magnox fuel.

DESCRIPTION OF THE INVENTION

In a preferred embodiment of the present invention, the separatingmember comprises a substantially flat solid surface adapted forvibrational motion. In a particularly preferred embodiment saidvibrational motion comprises a combination of vibrational motion in theplane of the separating member and in a direction perpendicular to theplane of the separating member.

In such an embodiment, the separating member comprises a tray which ismounted on a supporting member comprising inclined leaf springs. Asemi-solid viscous mass which incorporated solids material is placed onthe upper surface of said separating member. In operation, anelectromagnet is used to impart the vibrational motion and the magneticfield is applied such that the separating member is pulled through anarc imparting vibrational motion having both a vertical component in anupwards direction, and a horizontal component in the direction of theedge of the separating member that does not comprise a perimeter member.Successful results may be obtained by operating at a frequency of 18 Hzwith a horizontal amplitude of 10 to 12 mm.

Under the influence of such vibrational motion, the solids on thesurface of the separating member leave contact with the said surface andare thrown forwards towards the edge of the member that does notcomprise a perimeter member. As the process continues, the solids arethrown further in that direction and, therefore, eventually reach theedge of the member and are removed therefrom under the influence ofgravity.

Thus, directional vibrational motion is provided by the inclination ofthe leaf springs, which thereby impart sufficient vertical accelerationto the solid material on the tray for it to be thrown upwards andforwards, whilst the remainder of the semi-solid viscous mass hasinsufficient rigidity to be thrown upwards in the same manner and,hence, the segregation effect occurs. In practice, it is also generallyfound that the sticky nature of semi-solid viscous materials results intheir having significantly greater adhesion to the surfaces ofseparating members that is the case with solid materials, therebyfurther enhancing the separation process.

The method of the invention shows great advantages over the methods ofthe prior art in that it is able to provide rapid and efficientseparation of solids from semi-solid viscous masses. It also avoids thenecessity for the dilution of such viscous masses with copious amountsof water, which is designed to reduce their viscosity and improve theefficiency of separation. Whilst satisfactory separations havepreviously been obtained in this way, the increased volumes of effluent,as well as the higher resource and energy requirements of suchprocedures are extremely undesirable, and such disadvantages can beavoided by the use of the method of the present invention.

1. A method for the separation of solids from a semi-solid viscous mass,said method comprising treating a solids-containing semi-solid viscousmass in an apparatus comprising a separating member incorporating asubstantially flat solid surface and a supporting member, wherein saidseparating member is adapted to selectively impart directional momentumto said solids, thereby facilitating separation of said solids from saidsemi-solid viscous mass without dilution of said semi-solid viscousmass.
 2. The method as claimed in claim 1 wherein said separating memberis attached to and supported by a supporting member.
 3. The method asclaimed in claim 2 wherein said separating member is attached to andsupported by said supporting member such that said separating member isdisposed at an angle close to, but slightly displaced from, thehorizontal.
 4. The method as claimed in claim 3 wherein said separatingmember is disposed at an angle of between 1° and 10° from thehorizontal.
 5. The method as claimed in claim 4 wherein said angle isbetween 2° and 5° from the horizontal.
 6. The method as claimed in claim5 wherein said angle is around 3° from the horizontal.
 7. The method asclaimed in claim 1 wherein said separating member comprises asubstantially flat solid surface, the surface of which demonstrates adifferent degree of adhesiveness to the solids than to the remainder ofthe semi-solid mass.
 8. The method as claimed in claim 7 wherein thesurface of the separating member is fabricated of a material that adifferent degree of adhesiveness to the solids than to the remainder ofthe semi-solid mass.
 9. The method as claimed in claim 1 wherein saidseparating member comprises a substantially flat solid surface adaptedfor vibrational motion.
 10. The method as claimed in claim 9 whereinsaid vibrational motion is imparted so as to cause displacement of saidsolid particulate material in a substantially horizontal direction alongsaid separating member and also in an upward direction away from thehorizontal.
 11. The method as claimed in claim 10 wherein saidvibrational motion comprises a combination of vibrational motion in theplane of the separating member and in a direction perpendicular to theplane of the separating member.
 12. The method as claimed in claim 11wherein said vibrational motion comprises a combination of horizontalvibrational motion and vertical vibrational motion.
 13. The method asclaimed in claim 12 wherein said vibrational motion is imparted by theapplication of mechanical and/or electromagnetic forces.
 14. The methodas claimed in claim 13 wherein said mechanical forces are imparted bymeans of an out of balance motor drive.
 15. The method as claimed inclaim 13 wherein said electrical forces are imparted by means of anelectromagnet.
 16. The method as claimed in claim 13 wherein thefrequency of the applied vibrational motion is in the region of from 5to 50 Hz.
 17. The method as claimed in claim 16 wherein said frequencyis in the region of from 10 to 30 Hz.
 18. The method as claimed in claim17 wherein said frequency is in the region of from 15 to 20 Hz.
 19. Themethod as claimed in claim 13 wherein the amplitude in the plane of theseparating member is in the region of from 2 to 30 mm.
 20. The method asclaimed in claim 19 wherein said amplitude is in the region of from 5 to20 mm.
 21. The method as claimed in claim 20 wherein said amplitude isin the region of from 10 to 15 mm.
 22. The method as claimed in claim 1wherein said separating member comprises a substantially flat solidsurface comprising a tray or plate which additionally comprisesperimeter members attached to the edges of said separating member anddisposed substantially perpendicularly to said substantially flat solidsurface, with the proviso that one edge of said separating member doesnot comprise a perimeter member.
 23. The method as claimed in claim 22wherein, in operation, said separating member is disposed with the edgethat does not comprise a perimeter member above the horizontal.
 24. Themethod as claimed in claim 22 wherein said separating member comprises atray or plate which is rectangular in shape, and three of the four sidescomprise a perimeter member, whilst the fourth side does not include aperimeter member.
 25. The method as claimed in claim 24 wherein saidseparating member is attached to the supporting member by means of theremaining two sides of the rectangular member, perpendicular to andadjacent said fourth side.
 26. The method as claimed in claim 25 whereinsaid supporting member is any member suitable to support said separatingmember such that said separating member is disposed at an angle closeto, but slightly displaced from, the horizontal.
 27. The method asclaimed in claim 26 wherein said supporting member comprises inclinedleaf springs.
 28. The method as claimed in claim 25 wherein saidseparating member is movably attached to said supporting member.
 29. Themethod as claimed in claim 28 wherein said separating member isrotatably attached to said supporting member.
 30. The method as claimedin claim 1 wherein said semi-solid viscous mass comprises a sludge,industrial sludge, waste sludge, slate sludge or Magnox fuel wastesludge. 31.-33. (canceled)
 34. The method as claimed in claim 1 whereinsaid solids are solid objects or substances, or solid particulatematerial.
 35. The method as claimed in claim 34 wherein said solidobjects are machinery parts, small boulders, discrete pieces of slate,corroded cladding from Magnox fuel. 36.-39. (canceled)